Afarensis

I always get a great deal of amusement when Luskin writes about paleoanthropology.His latest effort is no exception. Casey, you see, has been studying about Lucy and of fossils pertaining to human evolution for years, and even links to the dreck he published in ISCID as proof, so of course he had to go.

Before going further, the following posts look at Lusin's ISCID paper:

• Note that Brayton completely ignored the arguments put forth in the links I provided in my last post, says Bombadill
• Primates and Such (One from the Archives)
• Plesiadapiformes (One from the Archives)
• Adapidae, Omomyidae and Anthropoid Origins (One from the Archives)
• Intelligent Design and Human Evolution: Part II (One from the Archives)
• Intelligent Design and Human Evolution: Part III (One from the Archives)
• Intelligent Design and Human Origins:The Final Post (One from the Archives)

One point to take away from the above is that it takes far more work to correct the distortions and misunderstandings frequently peddled by Luskin than it does for Luskin to peddle them. His article on Lucy is a case in point.

Casey likes to complain about how he is treated by evolutionists so I won't accuse him of lacking intellectual integrity and being deliberately deceptive in his post. Unfortunately, since I have ruled that out of bounds, the only other explanation is that he doesn't know what he is talking about and is unfamiliar with basic academic procedures for quoting and citing the work of others.

Let's start at the beginning.

Luskin's critique is divided into five sections. The first has to do with Lucy's completeness and with the prospect of commingling. Here is Luskin:

The first thing my friends and I noticed when seeing Lucy's bones was the incompleteness of her skeleton. Only 40% was found, and a significant percentage of the known bones are rib fragments. Very little useful material from Lucy's skull was recovered. (This seems to be common: many of the replica skulls of early hominids at the exhibit were clearly based upon extremely fragmentary pieces.) And yet, Lucy still represents the most complete known hominid skeleton to date.

Johanson et al 1982 provide a complete inventory of A. L. 288-1. The skeleton is composed of 76 elements of which 31 are ribs or rib fragments. All bones are not created equal however. A bone or bone fragment that contains diagnostic morphology is worth a lot. The 45 pieces that are not ribs tell us quite a bit about Lucy. Having said that, there are a number of skeletons out there that are almost as complete as, or more complete than Lucy. Little Foot springs to mind, as does OH 62, KNM-ER 3735 (not quite as complete as OH 62 or Lucy), KNM-ER 1808, KNM-WT 15000, and quite a few Neanderthals.That being the case Casey tries to cast some doubt:

In a video playing at the exhibit, Johansen admitted that when he found Lucy, he "looked up the slope and there were other bones sticking out." So this was not a case where the bones were found together forming a contiguous skeleton, but rather they were scattered across a hillside. At one point, Johansen even says that if there had been only one more rainstorm, Lucy's bones might have been washed away, never to be seen again. This does not inspire confidence in the integrity of Lucy's skeleton or its proper reconstruction: If the next rainstorm could wash Lucy away completely, what happened during the prior rainstorms to mix-up "Lucy" with who-knows-what? How do we know that "Lucy" doesn't represent bones from multiple individuals or even multiple species?

Oh snaps! Busted. Okay, I admit it Lucy is the commingled remains of rhinos, monkeys, and horses. I'm sorry, I was kidding you a little. Just wanted to link to those three articles because they say some interesting stuff about the evolution of rhinos, monkeys, and horses. More importantly, they demonstrate that a wide variety of bones from a wide variety of species are found during the course of a dig. Consequently, it is a good idea to be able to separate the bones paleoanthropologists are interested in from those other folk (paleontologists, zooarchaeologists, and other scruffy, unsavory types) might be interested in. Looking at the evolution of suids proved very helpful - but that's a story for another post. One way of doing that is to actually know something about skeletal morphology that way you can tell if your hominin has been mixed with who-knows-what, it's not just a matter of duplicate bones. Size and gender also play a role. As does understanding the taphonomic history of the bones, the depositional environment, and the stratigraphy of the site. Quite a bit of time has been spent, and is still being spent on the stratigraphy at Hadar. Casey has, of course "...studied about Lucy and other fossils..." , so I am much surprised that he didn't mention this.

In the second section Casey tries to cast doubt on the bipedality of Lucy by quoting from a News and Views article by Collard and Aiello. The Collard and Aiello article reports on a "letter" to Nature by Richmond and Strait called Evidence that humans evolved from a knuckle-walking ancestor. In that paper Richmond and Strait claim to do two things. First they provide evidence that Australopithecus anamensis and A. afarensis both share wrist morphology indicative of knuckle-walking. They then argue that knuckle-walking is a synapomorphy that links the African apes and humans. Once upon a time, and not all that long ago, the relationships between chimps, gorillas, and humans was considered an unresolved trichotomy. Quite a few people argued that chimps and gorillas were more closely related to each other than either was to humans. Others argued, based on morphological and genetic evidence, that chimps and humans were more closely related. Richmond and Strait's results took away a crucial piece of evidence for the gorilla-chimp clade. Casey, having "...studied about Lucy and other fossils..." doesn't mention any of this. Of course, if Lucy really is the commingled remains of who-knows-what as Casey argued above, then none of this matters and one has to wonder why Luskin goes futher. But he does. Says Casey:

Lucy did have a small, chimp-like head, but as Mark Collard and Leslie Aiello observe in Nature, much of the rest of the body of Lucy's species, Australopithecus afarensis, was also "quite ape-like" with respect to its "relatively long and curved fingers, relatively long arms, and funnel-shaped chest."

Given that Luskin is dedicated to exposing the misreporting on evolution, I'm sure you will be shocked as I am to find that this is only kind-of sort-of what Collard and Aiello said:

The basic facts are not in dispute. A. afarensis has a combination of traits that is not seen among living primates. In some respects, A. afarensis is quite human-like (for instance in the foot structure, nonopposable big toe, and pelvis shape). In others, it is quite ape-like (relatively long and curved fingers, relatively long arms, and funnel-shaped chest).

Casey, mangles things even further a few sentences later when he says:

Due to their evolutionary preconception that Lucy was a bipedal precursor to our genus Homo, they call this plain evidence that Lucy knuckled-walked "counterintuitive." They suggest the possibility that "the locomotor repertoire of A. afarensis included forms of bipedalism, climbing and knuckle-walking." This is a tenuous proposal, however, as knuckle-walking is obviously very different from bipedal locomotion. Collard and Aiello suggest avoiding the "counterintuitive" evidence that Lucy climbed and knuckle-walked by discarding it as unused "primitive retentions" from her ancestors.

Again, here is Collard and Aiello:

By the same token, however, Richmond and Strait's argument undermines the idea that A. afarensis combined bipedalism with climbing, which many researchers have hitherto considered to be the best interpretation of the evidence. Can we assert that one set of ape-like characters indicates that A. afarensis was an able climber, while at the same time arguing that another, equally good, set of ape-like characters is indicative of nothing except the phylogenetic history of A. afarensis? If the knucklewalking characters are considered to be primitive retentions, must not the same hold for the other ape-like characters?

Are our only choices to accept that A. afarensis was a striding biped with a
large number of non-functional primitive retentions, or to have to take seriously the
counterintuitive idea that the locomotor repertoire of A. afarensis included forms of bipedalism, climbing and knuckle-walking?

It sounds to me like Casey has mischaracterized what Collard and Aiello are saying. Collard and Aiello are saying that if you dismiss knuckle-walking as a primitive retention you have to dismiss climbing as well (and vice versa). Collard and Aiello are arguing for consistency and asking a rhetorical question about the implications thereof. After talking about a Jeremy Cherfas article in New Scientist (an article widely cited by creationists - but hey ID is not creationism in a cheap tuxedo - that I have been unable to find) Casey ends this section by saying:

The only reason to discard Lucy's clear anatomical evidence that she climbed trees and knuckle-walked is the Darwinist preference for her to be a fully-bipedal ape that was on her way toward evolving into a human being.

This will come back to make Casey look like he needs to have "...studied about Lucy and other fossils..." a little bit more. In, well, a few sentences.

The next section is about Lucy's status as a transitional fossil. He starts it by saying:

Let's assume for the moment that Lucy was a fully bipedal ape: should that necessarily qualify her as a human ancestor? Given that the much earlier fossil record from the Miocene yields bipedal apes that supposedly evolved upright-walking completely independently from the line that supposedly led to humans, it would seem that the answer is clearly no.

Tsk. Tsk. Casey, admit it, you have never really "...studied about Lucy and other fossils..." have you? The reason I say this is the bit about bipedal apes in the Miocene. This comes from another News and Views article in Nature called Ecological apes and ancestors by Peter Andrews. Andrews discusses an article in Natureby Leakey, Feibel, McDougall, and Walker - which I seem to have misplaced my copy of, so if someone can send it to me I would appreciate it I have the article now). The Leakey et al describes new specimens from Allia Bay and Kanapoi and names a (at the time) new species Australopithecus anamensis. The specimens at Kanapoi were found in two levels. An older level dating to 4.1 MYA and a younger level dating to 3.5 MYA. The lower levels yielded a mandible with symphysis and complete dentition both of which shared some traits in common with the kenyapithecines and with Griphopithecus (both of which are fossil apes). The postcranial material, including a distal humerus found in 1967, come from the upper level are described as Homo-like by Andrews (a number of others have so described them as well, Leakey, Ward, and Walker, in a number of publications have denied this). This leads Andrews to say:

If the dating is correct, and if there is just one species represented at Kanapoi, it results in the remarkable combination of advanced Homo-like features of the postcrania (that is the humerus and tibia from the later deposits) with primitive jaws and teeth similar to those of Miocene apes.

Given that mix a little later Andrews says:

Rather than questioning which hominid lineage the Kanapoi species may be on, therefore, I would like to raise the question of how it differs from fossil apes. Could it, for instance, belong to a bipedal ape not on the hominine lineage? Based on the association of the Homo-like postcrania, could it belong to a hominine lineage separate from the australopithecines but more directly intermediate between fossil apes and Homo? If the upper and lower Kanapoi specimens prove to be taxonomically distinct, there is even the possibility of that one group may be related to humans and the other to apes.

So, to recapitulate, according to Casey knuckle-walking and bipedality are obviously different, and Darwinist preconceptions prevent us from seeing the truth about Lucy. Yet here we have Casey taking a cranial similarity to Miocene apes and creating a bipedal Miocene ape. The kicker is that A. anamensis was used in the Richmond and Strait article and displayed some of the same knuckle-walking morphology. After this Casey quotemines Hawks (something I have addressed here).

In the next section Luskin says:

Given that some leading experts would probably sharply disagree with some of the claims about Lucy at the Pacific Science Center's exhibit, it seems appropriate to quote an article in the Journal of Human Evolution which concluded that the lack of fossil data about Lucy necessarily prevents paleoanthropologists from making firm conclusions about her mode of locomotion and bipedal stature:

The conclusion is that Lucy's erect posture is unlike that seen in modern humans and is still a mystery. Not enough fossil data are yet available to make a final judgement on the nature of her erect posture. ... Prevailing views of Lucy's posture are almost impossible to reconcile. When one looks at the reconstruction proposed by Lovejoy and by Weaver, one gets the impression that her fleshed reconstruction would be a perfectly modern biped. But when one looks at the preliminary reconstruction recently shown at the Smithsonian, one gets the impression of a chimpanzee awkwardly attempting to stand on its hindlimbs and about to fall on its front limbs. ... To resolve such differences, more anatomical (fossil) evidence is needed. The available data at present are open to widely different interpretations. Until more fossils are recovered and until we have a better interpretation of human and non-human primate positional behavior, there is likely to be a continuing debate on the subject of Lucy's posture and locomotion. Lucy's erect posture still is a mystery.

(M. Maurice Abitbol, "Lateral view of Australopithecus afarensis: primitive aspects of bipedal positional behavior in the earliest hominids," Journal of Human Evolution, Vol. 28:211-229 (1995) (internal citations removed).)

Notice the bit about internal citations removed? Casey fibbed. This bit comes from the abstract:

The conclusion is that Lucy's erect posture is unlike that seen in modern humans and is still a mystery. Not enough fossil data are yet available to make a final judgement on the nature of her erect posture.

and this bit:

Prevailing views of Lucy's posture are almost impossible to reconcile. When one looks at the reconstruction proposed by Lovejoy and by Weaver, one gets the impression that her fleshed reconstruction would be a perfectly modern biped. But when one looks at the preliminary reconstruction recently shown at the Smithsonian, one gets the impression of a chimpanzee awkwardly attempting to stand on its hindlimbs and about to fall on its front limbs. ... To resolve such differences, more anatomical (fossil) evidence is needed. The available data at present are open to widely different interpretations. Until more fossils are recovered and until we have a better interpretation of human and non-human primate positional behavior, there is likely to be a continuing debate on the subject of Lucy's posture and locomotion. Lucy's erect posture still is a mystery.

Comes 17 pages later. I haven't finished reading this paper yet so I won't comment further. The final irony is Luskin's use of a 1981 News and Comment from Science:

A 1981 commentary in Science captured this precise problem with the insufficiency of the data regarding hominid fossils: "The field of paleoanthropology naturally excites interest because of our own interest in origins. And, because conclusions of emotional significance to many must be drawn from extremely paltry evidence, it is often difficult to separate the personal from the scientific disputes raging in the field." This quote seems highly applicable to Lucy's exhibit at the Pacific Science Center, as we see bold claims based upon very sparse evidence from a discipline where paleoanthropologists are discarding evidence which doesn't fit their vision of human evolution.

This comment may have been, arguably true in 1981 when the article was written. The article itself spends a couple of pages detailing the origins of the Johanson-Leakey kerfluffle. The rest of the article examines the changes that were then ongoing in the field and concludes with:

Despite the bickering, paleoanthropology is in pretty good shape. Fossils are easier to find now that geologists know more about which formations are likely to contain them (in the first 50 years of exploration, according to one author, only five hominid fossils were found). Also, says David Pilbeam of Yale University, "the kinds of questions now being asked are more answerable." Futile debates over eternal mysteries such as why did man develop such a large brain-are being abandoned in favor of more practical pursuits, such as multidisciplinary attempts to reconstruct the total physical environment of a particular creature.

Casey finishes by saying:

Whether you're a true believer in Lucy's status as a transitional form, or an apostate who suspects that her story and reconstruction could be largely myth, the Lucy exhibit at the Pacific Science Center is worth visiting (after all, even atheists visit holy relics due to their literary and cultural significance). So go see the exhibit, keep an open mind, and come to your own conclusions. Just be forewarned that regardless of what you believe, you're likely to walk away from Lucy feeling underwhelmed at the incompleteness of the fossil and the lack of clarity in the case for human evolution.

As Darwin himself noted,

"A fair result can be obtained only by fully stating and balancing the facts and arguments on both sides of each question."

It's a pity Luskin didn't take his advice.